In the manufacture of filler material for cigarettes and the like, many attempts have been made to remove particular constituents from tobacco. Various techniques previously proposed in the art have involved volatilizing certain components of the tobacco, for example, by steam or vacuum distillation, or extracting various components from the tobacco with one or more solvents or combinations of solvents or otherwise treating tobacco to provide a tobacco with satisfactory smoking qualities at reduced levels of tar and/or nicotine. However, the tobacco from which these components have been removed has generally been significantly changed by such treatments and often loses many of its desirable characteristics in the process.
Other techniques have been employed or suggested similarly for removing and recovering portions of a tobacco product for incorporation in another tobacco product. However, these techniques generally have been found to be limited in their scope and effectiveness and, often are complex and expensive to perform.
Among the various techniques which have been suggested in the prior art are the following:
U.S. Pat. No. 3,174,485 to Griffith et al. relates to a smoking product comprising tobacco and a flavor and aroma additive which may be obtained by a process which includes the steps of: heating tobacco at about 150.degree. C. and 0.1 mm Hg for 8 hours; condensing the volatile matter released from the tobacco at a temperature of about -78.degree. C.; dissolving the condensate in a light hydrocarbon solvent; extracting the resulting hydrocarbon soluble fraction, in successive washings, with aqueous solutions of 10% sodium carbonate and 10% acetic acid solutions; separating the acidic and basic fractions from the hydrocarbon solvent fraction and removing the hydrocarbon solvent at ambient temperatures under a moderate vacuum to leave a neutral distillate fraction. The neutral distillate fraction obtained from low temperature distillation and referred to as the concentrate is then fractionated by solid-liquid chromatography techniques to provide the desired compounds for addition to the tobacco.
U.S. Pat. No. 3,424,171 to Rooker relates to a process for the production of a nontobacco smoking product. The process comprises providing cured natural tobacco, removing the aromatics naturally contained therein by heating the tobacco, generally in a vacuum, for a protracted period of time at a temperature not exceeding its scorching point of about 350.degree. to 400.degree. F., for example, by dry heating, steam distillation or by using an inert gas, such as nitrogen or carbon dioxide, absorbing the volatilized aromatics on activated charcoal and thereafter extracting the aromatics from the charcoal, for example, by solvent extraction with ethyl ether or a halogenated alkane, and applying said extracted aromatics to vegetable matter to form a smokable product.
South African Pat. application No. 72/3935 to Reemtsma relates to a method for obtaining tobacco aroma substances in which the tobacco is subjected to an extraction treatment with certain solvents or solvent mixtures, isolating only those components which are soluble in said solvent and, after removing solvent, subjecting the components to heat treatment between 30.degree. and 260.degree. C. The purpose of the process is to isolate certain aroma substances free, as far as possible, of undesired associated substances.
In J. Roerasde and C. R. Enzell, J. Agr. Food Chem., Vol. 20, No. 5 (1972) pages 1035-1039, there is described:
. . a process where tobacco volatiles were obtained by passing air through cut tobacco at room temperature, and absorbing the volatiles in activated charcoal. It is stated that the use of an inert gas would constitute a safeguard against oxidation. PA1 Burley tobacco was heated at 150.degree. C. and 1 mm for 48 hours. Released volatiles were collected in a trap maintained at -50.degree. C. Analysis and identification of compounds are reported.
In a paper by R. R. Johnson and J. A. Nicholson, presented at the 18th Tobacco Chemists' Research Conference (1964), there is described:
Despite all of the methods which have been worked on in the past, no completely satisfactory method has been found for obtaining, by simple means, a desirable fraction of flavor factors derived from tobacco. The present invention provides a method for simply removing from tobacco a selected set of volatile flavorants normally produced by the tobacco and forming a part but only a part of the smoke which is delivered to the smoker. These flavorants evolve from the tobacco in a narrow and well defined temperature range in a very short period of time and at atmospheric pressure. The thus isolated flavorants may be combined with another smoking material to enhance the flavor of its smoke. The present process offers advantages over the prior art and particularly Griffith in that it is unnecessary, and, in fact, undesirable to isolate individual components of the initial condensate. There is no assurance that the particular components isolated at 150.degree. C. and 0.1 mm mercury during eight hours by Griffith et al. can truly reproduce the flavor of tobacco smoke, whereas our mixture, although of complex and largely unknown analysis, does, in fact, so reproduce cigarette smoke flavor. Simply by collection and preservation of the condensate, we have captured precisely and essentially all of those flavors of tobacco smoke which are generated by the tobacco itself, and which confer upon tobacco smoke its typical characteristic organoleptic properties. The present invention also provides a number of other benefits, as will be described in greater detail later in this specification.